Digital X-ray detectors are classified into indirect-conversion-type X-ray detectors and direct-conversion-type X-ray detectors.
In indirect-conversion-type X-ray detectors, X-rays are converted into visible light using a scintillator, the visible light is converted into an electrical signal using a photodiode, and the electrical signal is detected. Meanwhile, in direct-conversion-type X-ray detectors, a photoconductor for directly generating an electrical signal through absorption of X-rays is used.
In this way, a direct-conversion-type detector is able to detect an electrical signal directly converted from X-rays, thus exhibiting high resolution, conversion efficiency and collection efficiency to thereby reduce radiation poisoning, but is currently problematic because of difficulty in commercialization.
In this regard, a photoconductor used for the direct-conversion-type detector needs to satisfy various properties, and photoconductors proposed to date, such as a-Se, CdTe, HgI2, PbI2 and PbO, have many defects.
a-Se suffers from high application voltage, low sensitivity and a charge-trapping phenomenon, and thus the use thereof as a photoconductor is limited.
Furthermore, CdTe, HgI2, PbI2 and PbO are disadvantageous because of complicated processing and high price, make it difficult to manufacture a large-area detector, and require a long period of time to realize mass production, and techniques for reproducible fabrication are currently insufficient.
Thus, there is an urgent need for a photoconductor that enables the mass production of detectors at low cost while satisfying diverse properties required of the photoconductor, in addition to the materials developed to date.